It is known that the conventional art for cooling of a forming mold, in which the forming mold includes a cooling channel and an atomized coolant liquid as a refrigerant is flowed with compressed air in the cooling channel (see JP-63-299848A). In this conventional cooling art, the refrigerant consisting of the coolant liquid and the compressed air is flowed into the cooling channel, and the air blow and heat of evaporation of the coolant liquid make the forming mold cool, in which the refrigerant passes through the cooling channel taking heat from surroundings.
It is also known that the conventional cooling for the forming mold, in which a flux of the atomized coolant liquid is controlled for adjustment of cooling (see JP-H11-170257A).
In the both conventional cooling art, the exhaust gas from the cooling channel contains a lot of water vapor. The vapor is emitted around the mold, which causes the heightening of humidity in the factory, so that the working atmosphere lowers. Particularly, with respect to a casting mold, the heightened humidity lowers the quality of molten metal.
The atomized coolant liquid flowed into the cooling channel of the forming mold is rapidly evaporated in the cooling channel and the volume of the coolant liquid is expanded, thereby the back pressure of the cooling channel increases. Due to the increase of back pressure, the boiling point of the coolant liquid is heightened and a part of the refrigerant is liquefied. Further, the turbulence of the coolant occurs and unfortunately the equal cooling is blocked.
Moreover, the cooling channel, into which the refrigerant including atomized coolant liquid and air is flowed, becomes high temperature, thereby the air and iron of the wall of the cooling channel react with water. Thus, there occurs rust that degrades the mold or scale that lowers the cooling efficiency. To avoid the occurrence of the rust at the wall of the cooling channel, it is conventionally known to eliminate dissolved oxygen of the coolant liquid circulated in the cooling channel (see JP-H10-109092 A). However, when the atomized coolant liquid is flowed with the compressed air, the iron of the wall of the cooling channel does not react with the dissolved oxygen in the coolant liquid but with oxygen in the air. Therefore, the elimination of the dissolved oxygen may fail to prevent the rust.